THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.

WOLF BLITZER, CNN ANCHOR: Happening now: terror capture. Two of the world's most wanted, they are now in custody, suspected of involvement in both the Paris and Brussels massacres. Could one of them be the so-called man in the hat caught on surveillance video before and after the airport bombing? Why has it taken so long?

[17:00:18] Heightened alert. An earlier arrest may have triggered the slaughter in Brussels. Could the latest arrests serve as a signal to other cell members to launch new terror attacks? Why authorities may need to learn information very, very quickly.

Muted Trump. The statistics show that he's staying out-of-sight today, saying he's busy running his business. But by staying home, is he leaving delegates for Ted Cruz to grab?

And backtracking. After angrily clashing with protesters, Bill Clinton now says he almost wants to apologize. And Bernie Sanders also backing off his claim that Hillary Clinton is not qualified to be president.

We want to welcome our viewers in the United States and around the world. I'm Wolf Blitzer. You're in THE SITUATION ROOM.

ANNOUNCER: This is CNN breaking news.

BLITZER: We're following breaking news. Two of the world's most wanted terror suspects have been captured in Brussels. Both are linked to the massacres there and in Paris. One, Mohamed Abrini, is suspected of driving those involved in the terror attacks and taking part in last month's bombings of the Brussels airport. Prosecutors are trying to learn if the so-called man in hat, shown on surveillance video right before the airport bombings and then calmly leaving the scene afterwards.

The other suspect is being linked to the bombings at a Brussels subway station. There's concern right now that police must act quickly to learn if the arrest could signal more cell members to launch fresh attacks.

And a shift in strategy in the Republican race. As Ted Cruz chases big donors in Las Vegas and hunts delegates this weekend in Colorado, Donald Trump is cancelling travel plans, focusing in on his home state of New York. The Cruz campaign has been active behind the scenes for months. Now

Trump's campaign is preparing for a possible delegate fight at the GOP convention this summer in Cleveland. I'll speak with Congressman Patrick Murphy, the House Intelligence Committee.

And our correspondents, analysts and guests, they'll have full coverage of all the day's top stories.

We begin with our breaking news, the arrest of two very dangerous terror suspects. CNN's Brian Todd is here. He's been digging into this.

What you are learning, Brian?

BRIAN TODD, CNN CORRESPONDENT: Wolf, a major break for counterterror forces in Europe. A dragnet in Brussels has brought in two very dangerous men: Mohamed Abrini, believed to have been a key operative in Paris, probably also in Brussels; and Osama Krayem, a man who may have been on the platform before the metro train attack in Brussels.

Belgian authorities have been under pressure to sweep up this single terror cell believed to have carried out both the attacks in Paris and Brussels.

(BEGIN VIDEOTAPE)

TODD (voice-over): Captured alive in Brussels, two men believed to be among the world's most wanted and dangerous terrorists. Men suspected of involvement in the Paris and Brussels attacks.

One is 31-year-old Mohamed Abrini. Belgian network BRT reports Abrini could be the so-called man in white, the mysterious third attacker at the Brussels airport, seen in this surveillance footage, walking next to the two suicide bombers. But prosecutors are not yet ready to make that link.

THIERRY WERTS, BELGIAN PROSECUTOR'S SPOKESMAN: At the moment, the investigators are verifying whether Abrini Mohamed can be positively identified as the third person present during the attacks in Brussels National Airport, the so-called man in the hat.

TODD: That man slipped away and was seen in this surveillance footage making his way through Brussels after the attacks. But Mohamed Abrini is still believed to have played a key operational role in the Paris assaults.

PAUL CRUICKSHANK, CNN TERRORISM ANALYST: Forty-eight hours before the attacks, he transported the attack teams from Belgium to Paris.

TODD: Abrini was seen in surveillance footage at a gas station in France two days before the Paris attacks. He's with Saleh Abdeslam, the Paris suspect whose brother blew himself up in Paris. Abrini is believed to have driven Abdeslam to Paris for the attacks. Authorities say Abrini drove a Renault Clio, used in Paris. Saleh Abdeslam is already in custody after apparently aborting his mission in Paris, making his way to Brussels, and hiding out for four months. He was captured just four days before the Brussels attacks.

Another key suspect arrested the today, Osama Krayem. He is believed to have played an operational role in the Brussels bombings.

CRUICKSHANK: One possibility is that he was the man seen on the TV images out of Brussels metro stop with a metro bomber.

TODD: A key concern tonight: will the two men just captured give authorities any intelligence?

MICHAEL BRAUN, FORMER DEA CHIEF OF OPERATIONS: They want to know about tactics, techniques and procedures. You know, how did they pull this event off, start to finish? What kinds of -- exactly what kinds of devices they were using? Who built them? What other cell members are involved?

[17:05:13] TODD: And European intelligence officials believe there are members of this same terror cell still out there.

CRUICKSHANK: European security agencies believe there are more than a dozen individuals still at large who played some kind of logistical support role for the cell. A lot of concern of what they may do next.

(END VIDEOTAPE)

TODD: And investigators have a huge challenge tonight, with the two men just captured. Their alleged cohort, Saleh Abdeslam, who is also believed to have played key roles in both Paris and Brussels, is thought to have not given up very much information at all to authorities so far. So, Wolf, these two may not talk.

BLITZER: Brian, as you know, one major suspect arrested today, this guy, Osama Krayem, also may have gathered the materials used in the Brussels bombings. What do we know about that?

TODD: That's right, Wolf. He's the man in the center here. Prosecutors say the second person seen in the train station, who they say they are trying to verify, was this man, Osama Krayem, was videotaped in a shopping mall in Brussels, buying bags that were later used in the Brussels attacks.

BLITZER: All right. Brian Todd, thank you.

Let's turn to our chief national security correspondent, Jim Sciutto.

Jim, there's concern that these arrests could actually spark another round of terror attacks.

JIM SCIUTTO, CNN CHIEF NATIONAL SECURITY CORRESPONDENT: The beauty of these arrests are that you have taken two major terror suspects off the streets, connected to two of the most brutal attacks in Europe in the last ten years. The danger is that when you do that that other members of this network

have concern that they may be next, and any details of plots currently under way could come out in interrogations of these two suspects so that they might act out of a -- just fear that they will be caught themselves.

You can argue that after Saleh Abdeslam was caught, it was three days later that we saw the Brussels attack, that perhaps those attacks were accelerated because of concern from other members of the cell that they could be captured in those attacks toward it.

BLITZER: We're showing some live pictures at the bottom right-hand corner of the screen -- over there you can see it -- where there's -- apparently, there's more arrests under way, more searches under way, even as we speak right now. Those are live pictures coming in from Brussels.

Apparently, Saleh Abdeslam, when he was picked up a few days before the terror attacks at the Brussels airport, he didn't talk; he didn't say anything. He didn't provide anything. But there was concern that other -- other of his colleagues, shall we say, his cohorts were afraid he might. That's why they accelerated that attack.

SCIUTTO: Absolutely. And even if he doesn't talk, concerned that if they got close to him, just as they've gotten close to these suspects, and they were to capture them, that they would have other intelligence that might be that they could get other members of the network next. That was a real concern.

Listen, we've talked about this many times. The level of terror alert in Europe is already very high. They're not going to officially raise it. But clearly, they're going to be watching very closely so that doesn't happen.

BLITZER: While this is a win, the arrest of these two terror suspects, still a lot of criticism of what's going on over there.

SCIUTTO: There is. We've heard it from U.S. officials, concern that they're not sharing -- the European intelligence services are not sharing enough information with the U.S. about people on their own terror watch lists. That's between the U.S. and Europe but also within Europe.

I've heard from U.S. intelligence and counterterror officials that they have a pre-9/11 mentality. They're not sharing. They're not playing nicely together. In fact, sometimes within their own countries in terms of sharing between a single country's own differing agencies.

And that that's something they have to do better. The impression I hear from the U.S. officials is that they are doing better, but they have to accelerate that to prevent attacks going forward.

BLITZER: Once again, those are live pictures in the bottom right hand corner of the screen, showing -- these are live pictures right here. Looks like there's more arrests, more searches under way as we speak. We'll update our viewers. Jim Sciutto, thanks very much.

Joining us now is a member of the House Intelligence Committee, Democratic Congressman Patrick Murphy of Florida.

Congressman, thanks very much for joining us. Why do you believe it took so long to capture this terror suspect, Mohamed Abrini?

REP. PATRICK MURPHY (D), FLORIDA: That's exactly the problem, listening to your previous guests, they really hit the nail on the head. This is their 9/11 moment for them, and we are seeing exactly some of the issues and the lack of really sharing information, the lack of technology, and the lack of coordination amongst various law enforcement officials and the intelligence community.

So this is their moment. This is their conversation that really needs to unfold. I think America plays a very important role in helping them do that.

Because the truth is, in this globalized world we live in, what is a problem there could be a problem here tomorrow and vice versa, and we've already seen that play out already.

You know, additionally, I think it's important to note this conversation, that is still playing out in this country and needs to play out in Europe is this -- this really question of privacy versus safety and where is that going to fall? In times like this, you see, obviously, the pendulum swing and the need of more safety, more technology to prevent these, you know, atrocities from ever happening.

[17:10:05] BLITZER: These are massacres that took place.

Mohamed Abrini, as you know, Congressman, was one of Europe's most wanted. What will his arrest mean in terms of trying to stop other terror attacks?

MURPHY: Well, you know, you alluded to it earlier. Of course, not only the United States but all European countries need to be on continued high alert. Oftentimes after a suspect is captured, a terrorist is captured, there are incidents that happen immediately after because of the fear.

What we are learning is how closely knit these networks are, how well they understand a lot of European -- Europe's and Americas technology and doing what they can do to evade that.

We've got to do a better job, especially once we get one of these, whether it's in Europe or whether it's the United States, of getting down to the bottom and seeing what else is planned in the immediate future and how all these cells are connected.

BLITZER: As far as you know, Congressman, are there other plotters in the Belgium terror attacks who remain at large?

MURPHY: As far as I know, not yet. I don't know any of that information. When I get back to Washington, D.C., next week, we will be briefed on this matter. We'll know more information. But everything I know you know. It's all open source information at this point for me.

BLITZER: Saleh Abdeslam, he was arrested, what just four days before the March 22 Brussels terror attacks at the airport, the metro station there. How concerned are you now that Mohamed Abrini's arrest could actually trigger another terror attack?

MURPHY: Well, Europe is already on high alert and needs to remain in that same status, as does the United States of America. Because what we see historically is, once they are captured, once they're taken in by law enforcement is some of the other potential attacks that are planned are sped up. And they want to make sure that they are not caught, that nobody talks, in essence, and that they carry out these terrible, terrible actions.

So, we've got to be on high alert but do a better job of coordinating, of getting and using technology, to prevent these from happening, getting their information they may have. Whether it's a computer, whether it's a cell phone, being sure we see what's in there and potentially who else they're talking to and where they are talking to give law enforcement that heads up.

BLITZER: I've been told, Congressman, by U.S. counterterror officials that they worry right now, especially after a high-profile arrest like this, a setback, clear setback to ISIS, that the ISIS leadership in Raqqah may order some other terror attack just to prove that they are still very, very capable of unleashing these kinds of attacks. How worried are you about that?

MURPHY: Well, unfortunately, that is the reality. They are losing ground in Syria, but they are showing their breadth and, really, just what a global network this is. And you know, unfortunately, whether we want to call this ISIS, whether we want to refer to it as terrorism -- whether it's al Qaeda, al Nusra, whatever organization it is -- we are continuing to see more and more of it popping up around the world. More acts of violence and extremism, which I think really shows the importance of law enforcement, of coordination around the world, using technology to our advantage but also doing a better job of integrating some of these refugees that are, you know, really around the world, especially in Europe right now. Making sure they are assimilating better into the communities. America does a better job of that than Europe, but we've got a lot to learn.

BLITZER: Congressman, I want to show you these live pictures coming in from Brussels. You see it's 11:13 p.m. over there in Brussels right now. We're getting new information. We'll take a quick break. We'll resume the breaking news coverage right after this.

(COMMERCIAL BREAK)

[17:18:13] BLITZER: Back to the breaking news. Take a look at these live pictures coming in from Brussels right now, more police raids, arrests apparently underway right now. We're staying on top of the story.

Earlier, two of the world's most wanted terror suspects, linked to the massacres in both Paris and Brussels, they were arrested. We're back with Democratic Congressman Patrick Murphy of Florida, a key member of the House Intelligence Committee.

Congressman, the Belgian broadcaster BRT reports that Mohamed Abrini was also possibly that so-called man in the hat sought in connection with the Brussels attacks, the suspect seen on that surveillance video walking next to two of the suspected suicide attackers. If that's the case, this would be a major breakthrough in learning about the Brussels attacks, wouldn't it?

MURPHY: Yes, it certainly would, and that's the speculation at this point. There's obviously still a lot of information to uncover here. But that is a first step in this.

BLITZER: Have you been told that that individual, Abrini, is in fact that man in the hat, as he's been called, that suspect?

MURPHY: No, it hasn't been confirmed to me. I'm, you know, still in Florida. When I get back to the Intel Committee next week, we'll have a thorough briefing on this matter.

BLITZER: Out justice correspondent, Pamela Brown, is reporting that the head of the U.S. terror watch list worries that Europe is not taking full advantage of the data the U.S. provides to them. Are European officials not closely monitoring what's going on or they're not doing a good enough job?

MURPHY: Well, what you're seeing in some countries you're seeing them do a much better job of this, but it's not consistent across the board. And in Europe the borders are so porous, people are moving from one country to another without any scrutiny, without any questions being asked.

So while it might be stronger in one country, if you go 50 miles away and it's weak, what does it ultimately matter? So that's the important moment here, why I think this is such a learning experience for Europe.

And that's why many people are calling this their 9/11 moment to learn, if we're going to have these open borders, we better get to the bottom of this information sharing and make sure we're all on the same page and make sure we are having more trust at all levels of law enforcement on the same page and using cyber to our advantage.

[17:20:23] The truth is the bad guys, these terrorists are certainly using it to their advantage and know what we're looking for, what we're not. And we have got to do a better job across the board globally to track these folks down.

BLITZER: As you know, the nightmare scenario that keeps a lot of U.S. counterterror officials awake at night is that one of these ISIS terrorists could actually slip into the United States, given the visa waiver program. They are, after all, citizens of friendly countries like Belgium or France or U.K. or Sweden, whatever. Is the U.S. on high enough alert right now?

MURPHY: Yes, well, you know, I don't know if you can ever say we're high enough on alert. What I do know is, being a member of the intel committee, in all of

our briefings, this is one of the areas we are spending the most time on. That law enforcement, that FBI, that all the various agencies are spending a tremendous amount of time, vetting the folks coming to this country. Making sure our borders are as safe as possible.

But, you know, this speaks, unfortunately, to the gridlock in Washington, D.C., and how, you know, common sense problems often aren't being addressed, how funding sometimes lacking for some of our intel, for some of our law enforcement officials.

And we have to make sure, in all areas we're putting partisanship aside, and especially when it comes to the safety of the American people.

BLITZER: We're going to continue to monitor the breaking news in this hunt for the terrorists.

We're also following major developments on and off the presidential campaign trail today. For the first time, Donald Trump's new delegate hunter is dropping hints about a strategy to make sure Trump wins the Republican nomination at the convention.

(COMMERCIAL BREAK)

[17:26:33] BLITZER: We're following the breaking news: more searches under way right now after the arrests of major terror suspects linked to the Paris and Brussels massacres.

But right now, we want to turn to new developments in the presidential race. While Ted Cruz heads west to pursue donors and delegates, Donald Trump has scrubbed travel plans, at least for today, staying in New York, at home.

Our political reporter, Sara Murray, is on the scene for us.

Sara, what is the latest? What's going on?

SARA MURRAY, CNN POLITICAL CORRESPONDENT: That's right, Wolf, Donald Trump is hunkering down here in the Empire State while his campaign recalibrates.

One thing we do know, though: They do not want to see this thing go to a second ballot at the convention. They are trying to have it locked up before they get to Cleveland.

(BEGIN VIDEOTAPE)

MURRAY (voice-over): Donald Trump stepping away from the trail to regroup and firing off a reminder that he has priorities beyond his bid for the presidency, tweeting, "So great to be in New York, catching up on many things. Remember, I am still running a major business while I campaign and loving it."

Trump laying low as his campaign crafts a plan to clinch the nomination before Cleveland.

PAUL MANAFORT, TRUMP CONVENTION MANAGER: The reality is Ted Cruz has seen his best day. The reality is this convention process will be over with sometime in June, probably June 7, and it will be apparent to the world that Trump is over the 1,237 number.

MURRAY: Trump's recently-named convention manager, Paul Manafort, making it clear he'll play a prominent role in the campaign from now on and report directly to Trump.

MANAFORT: I work directly for the boss. But I listen to everybody. But I have one man whose voice is louder than anybody else.

MURRAY: Manafort adding that his role is a sign Trump is ready to take a more strategic approach to the race.

MANAFORT: Because the campaigns come in stages, he also understood that there comes a time when winning isn't enough. But it's how you win and how much you win.

MURRAY: Meanwhile, Ted Cruz is still trying to make the case that he has a path to 1,237 delegates, even as his campaign hustles behind the scenes to prepare for a contested convention.

CRUZ: We have a clear path forward to get to 1,237 delegates. It's difficult. We've got to win, and we've got to win consistently.

MURRAY: Cruz telling CNN's Dana Bash, even as he vied to lead the party, he won't apologize to Senate Majority Leader Mitch McConnell for accusing him of lying.

DANA BASH, CNN SENIOR POLITICAL CORRESPONDENT: So no apology to Mitch McConnell? Because it could help you.

CRUZ: Look, my focus is not on Washington. That ain't going to happen. And if the Washington lobbyists want to see that happen, they can hold their breath a long, long time.

MURRAY: As Cruz and Trump took a day off the trail, John Kasich soldiered on and took a swipe at Trump along the way.

KASICH: We're not winning? We're winning on everything. We are still the strongest country by far in the entire world, and people ought to stop whining about America.

MURRAY: The Kasich campaign also going after Cruz on the airways, dismissing the Texas senator's chances of winning the nomination or the general election.

BLITZER: How likely is it that the Republican nominee will have to face an open or contested convention?

SPICER: Well, each contest that we get through -- tomorrow is Colorado; the week after is Wyoming, then that big prize, 95 delegates in New York the 19th.

[17:30:01] As each one of those passes by and either the candidate doesn't continue to rack them up and pursue the 1237, the -- excuse me, 1230 or 1237, then that likelihood become greater.

There are still paths for both Senator Cruz and Mr. Trump to get those 1237 bound delegates. But the percentages are about 60 percent for Mr. Trump and 85 percent for Senator Cruz that they need to rack up to get the bound delegates.

It's an important distinction, Wolf, that you -- there are people that might go into a convention with, say, 1200 bound delegates and have the support of 37. But until that vote occurs where a majority of the delegates gives someone that nomination, it would be an open convention.

BLITZER: The Trump strategist, Barry Bennett, told me, one of the top strategists, advisers to Trump, right now they need 60 percent of the remaining delegates to be guaranteed that magic number and Cruz needs about 90 percent.

SPICER: Right.

BLITZER: Or something like that. But this is what Barry Bennett said, if Trump wins all of New York's 95 delegates a week from Tuesday and he thinks that he will, then it goes down to like 50 percent or 55 percent which is much more doable.

SPICER: Well, sure, and again, if you think about it, any scenario where if you over perform what you need, you're going to need less going forward. And if you underperform, you'll need even a higher amount. So the math works, you know, to the point that wherever -- however you get it, I mean if you wracked them all up real quick. But I think there's no doubt, it was noted in the prior interview, that we're -- we are going to June 7th. Whether you've got that final group of states on June 7th.

BLITZER: California.

SPICER: California 172 delegates.

BLITZER: That's when they get --

SPICER: That's right.

BLITZER: Of the season. As you know, the Democrats have their super delegates, more than 700 of them. Republicans have what they are called the unbound delegates, 183 unbound delegates who can decide to go any way they want. Will they be the decisive element in all of this?

SPICER: They could. Sure. I mean, it's very possible, again, that, you know, Mr. Trump in particular has enough of a lead that he may not need them. But it's very possible that those delegates who were elected as unbound or undeclared delegates become important. I think -- but one thing that's really interesting, if you go to a state like Colorado and Wyoming, the next two contests coming up, Colorado tomorrow night, Wyoming next week. Those -- those delegates can run undeclared and remain unbound, but they can also run for a candidate.

So you can run as a Ted Cruz delegate or a John Kasich delegate, or a Donald Trump delegate. In that case, you do become bound. And so some of these states that do have unbound delegates allow the delegate to run bound to a particular candidate. That creates a second scenario, too, of how that math would work.

BLITZER: How would the RNC, the Republican National Committee, handle what some fear could be delegate intimidation?

SPICER: Well, I mean, we're going to have, you know, the most secure and best convention that's ever been put on. I just got back from Cleveland, the preparation is unbelievable. The city is excited. It's going to be phenomenal. We're going to make sure that our delegates are protected and safe, not just them but anyone who attends it. The members of the media, the guests at the convention, the candidates, the Secret Service and the local police have done a phenomenal job preparing. I don't think that's going to be an issue.

BLITZER: Will there be rules written preventing gifts, for example, being given by candidates to delegates out there who could potentially make a difference? Because there's some concern about that, as you know.

SPICER: So right now there's no prohibition on a delegate being interactive with, in the same way that a supporter can be interactive with a campaign. The rules committee could meet and say going forward when the convention starts, we hereby enact a rule that limits further gifts to X or Y, that would be something that the delegates get together, once they are arrive in Cleveland and decide that for the good of all, they want to put some kind of rules.

BLITZER: If the Cruz campaign or the Trump campaign or the Kasich campaign decide they want to do favors, they want to offer someone a free trip, something like that, is that -- is that OK?

SPICER: Well, as far as I know, it's legal. But that is up to the -- they would probably have to disclose it with the Federal Election Commission as they would any other campaign expenditure. Remember, this is no different than going in to an early state or a current state and trying to win the support of, you know, major activists or what have you, and saying hey, we'd like to, you know, have dinner with you or bring you to an event or what have you. But that currently goes on in the system now, which is -- I think you're going to see a little bit more attention to the delegates who might now have gotten the same attention than previously.

BLITZER: You think this all could come down to who has a better delegate operation in Cleveland?

SPICER: Sure, why not? I mean, that's part of the process. I mean, and part of what this whole process is about. It's winning the delegates. Getting them allocated to you and then ensuring that the delegates are selected, that are loyal to you and --

BLITZER: Because, you know, the trump supporters are going to be very, very upset. They're going to be very angry at the Republican Party, presumably, let's say Trump comes in just short of that 1237 magic number, let's say he's got 1200, but doesn't have 1237, and they all of a sudden a second, third ballot, they give it to somebody else. They're going to leave very, very angry. That could really hurt the Republican Party.

SPICER: Look, I think whoever doesn't win is not going to be excited. That's the nature of losing.

[17:35:01] BLITZER: But if it's that close.

SPICER: But I think -- hold on. But I think the important thing is that we are going to run the most open and transparent process that exists so that everybody, not just in the campaigns, but in the country, and I dare say the world, is going to watch how a process can work. A Democratic process where we go through in a very open and honest and transparent way and everybody gets to see the votes tally, everyone gets to see it happened live on television. And so what we want is that even for people who don't maybe farewell in Cleveland to walk away saying, hey, I was treated fairly. It was open. It was honest. But that's the role of delegates, remember, which is they get elected to come in and represent the people that elected them. So those are -- that's how the process works. And I expect it's going to work just the same this year in Cleveland.

BLITZER: And as you know, we're going to watch every step of the way.

SPICER: Yes. We are 100 days out tomorrow. It's exciting.

BLITZER: And well, we'll be there every step of the way.

Sean Spicer, thanks very much for coming in.

SPICER: Thank you. BLITZER: Much more coming up on the Democratic side, there's a lot of

activity going on today. We're going to take a closer look at the latest developments when we come back.

(COMMERCIAL BREAK)

[17:40:39] BLITZER: Today, we heard for the first time from Donald Trump's new delegate hunter who says he's reporting directly to Trump himself. Let's get some insight from our CNN political commentator Ana Navarro, our political commentator Michael Smerconish, he's the host of "SMERCONISH," seen Saturday mornings 9:00 a.m. Eastern right here on CNN, Real Clear Politics national political reporter Rebecca Berg, and CNN political commentator Peter Beinart, he's a contributing editor for Atlantic Media.

Michael, Paul Manafort, that's Donald Trump's new delegate expert, says he believes Trump will reach that magic number of 1237 delegates, the number he needs before the convention in Cleveland. On "NEW DAY" this morning, he downplayed Senator Cruz's effort to, quote, "steal delegates." Listen to this.

(BEGIN VIDEO CLIP)

PAUL MANAFORT, TRUMP CONVENTION MANAGER: You've got to understand what the game is. If the game is second or third or fourth ballot, then what he is doing is clever. But if there's only one ballot, what he's doing is meaningless. Because these stolen delegates, as he calls it, something we're going to be able to do as well in the next couple of weeks, these stolen delegates, they still have to vote for Trump on the first ballot.

(END VIDEO CLIP)

BLITZER: So, Michael, let's say Trump doesn't get to 1237 on that first ballot, what happens then?

MICHAEL SMERCONISH, CNN HOST, "SMERCONISH": I don't think he gets there at all. I think Paul Manafort, who's a seasoned veteran, recognizes that Donald Trump needs to get there before they arrive in Cleveland because the rules really don't favor Donald Trump on every successive ballot. And the reason I say that, Wolf, is because the party plays a greater role the further you get from that first ballot. Look at New York, it's the party that they are now putting up the individual. So Donald Trump could do well, win that primary on the 19th, get all 95 delegates but if it doesn't get him home, it's the party that's in control on the second, third and fourth ballot, and I think they'll be looking for a winner and won't feel an allegiance to Trump.

Pennsylvania, my home state, on April 26th a very odd system. An untethered, unbound kind of a system, what they tend to favor are party people. Those who have been the assistant committee man. You know, the local representative and so forth. And I think that Donald Trump is probably not their most favored candidate. They could be wedded to him on ballot number one but not thereafter. BLITZER: As you know, Rebecca, there are Republican conventions this

weekend, what, in both Colorado and Michigan. The Cruz campaign clearly on the ground. They're trying grab as many of those delegates as possible. How is the Trump campaign dealing with this?

REBECCA BERG, NATIONAL POLITICAL REPORTER, REAL CLEAR POLITICS: Well, these two states are a little bit different from each other. We can see in Michigan, we have what Manafort was talking about. So these delegates that will be bound to Trump on the first ballot. But on the second ballot or the third ballot, anybody's game so that's where people are trying to focus on organizing around a second ballot situation. And Trump does have a presence in Michigan, where actually there was a bit of news made when Mitt Romney's niece who lives in Michigan and is involved in party politics there, actually said she would remain supportive of Trump on the second ballot, which was something of a surprise.

Colorado is a little bit different because these are unbound delegates. So at the state convention this weekend, campaigns are trying scoop up as many of these delegates as they can. They are not bound on the first ballot. So that is a big deal. Cruz is actually going to be speaking there. He is organizing very well in Colorado and has already won most of the state's delegates. Donald Trump not coming to Colorado, not organizing well according to reports there. He's going to be at a big disadvantage in Colorado.

BLITZER: He's not personally going to be there, although his campaign says others representing him will be there.

Ana, Senator Cruz said yesterday, that anyone who expects him to apologize to the Senate majority leader Mitch McConnell for accusing him of lying last year should, quote, "hold their breath for a long, long time." How does a comment like that affect his ability to rally establishment types, anti-Trump Republicans behind him?

ANA NAVARRO, CNN POLITICAL COMMENTATOR: Look, I think, establishment types recognize what Senator Ted Cruz is. He is not a guy who played well in the sandbox. He is never going to win the Mr. Congeniality contest in the U.S. Senate. He probably won't get many more Senate endorsement. You almost have to drag him out, pulling teeth like you did with Senator Risch the other week. And I don't think that Mitch McConnell, who I know a little bit, is expecting an apology.

It would go completely against his nature, against Ted Cruz's nature and image. It would do him at this point, more harm than good.

[17:45:03] Donald Trump would have a field day if Ted Cruz asked Mitch McConnell for an apology. So I think strategically it's the right thing to do. I don't think Mitch McConnell expects it. I don't think anybody expects it, so I'm not going to be holding my breath. We either support Ted Cruz because we are against Trump or we don't support him because he was obstructionist and didn't play well with his Senate colleagues. Those are the choices.

BLITZER: Peter Beinart, let me get you into this, on the Democratic side, as you know Bill Clinton tried to do some damage control after that heated exchange he had with the Black Lives Matter protesters yesterday. Listen to what he said earlier.

(BEGIN VIDEO CLIP)

BILL CLINTON, FORMER UNITED STATES PRESIDENT: I did something yesterday in Philadelphia I almost want to apologize for, but I want to use it as an example of the dangers threatening our country. Half of us are so mad all the time because we think the game has been rigged. Well, it has. The question is, how you're going to unrig it?

(END VIDEO CLIP)

BLITZER: So, Peter, does this almost apology hurt or help the Clinton campaign effort?

PETER BEINART, CNN POLITICAL COMMENTATOR: Well, the whole incident hurts Hillary Clinton. I mean, I actually think it was a very interesting debate and in some ways the example of a debate we should be having. I think Bill Clinton was making some useful points about the way in which the discussion about crime and race was perceived very, very differently including by many African-American politicians back in the '90s and how it is today. But it takes Hillary Clinton off message.

And this was the fear always about Bill Clinton. That he did this in 2008, he took her off message. She has made a very decision that she's going to repudiate the tough on crime legacy of the Clinton administration of the 1990s, focusing on ending mass incarceration, take a conciliatory attitude towards Black Lives Matter, and he did the opposite. And despite his apology, I think it throws her off message.

BLITZER: All right, I want everybody to stand by. I also want to remind all of our viewers to tune in once again tomorrow morning, every Saturday morning, 9:00 a.m. Eastern for "SMERCONISH," a very smart show.

We continue to follow the breaking news in Belgium as well after the capture of two major suspects in the Paris and Brussels attacks. There are new police raids underway right now. We have live pictures coming in.

We're also getting new information. We'll have the very latest much more right after this.

(COMMERCIAL BREAK)

[17:51:40] BLITZER: In the Democratic presidential race today, both Senator Bernie Sanders and former president Bill Clinton are trying to take back some of their heated words out there on the campaign trail.

Let's go to our national correspondent Suzanne Malveaux.

Suzanne, tell us about the latest backtracking. What's going on over you?

SUZANNE MALVEAUX, CNN NATIONAL CORRESPONDENT: Well, Wolf, as you know, as we both know covering President Bill Clinton, these flashes of public anger are very rare but we saw that yesterday in his confrontation with the protesters with Black Lives Matter.

I talked to Clinton supporters and quietly they say they do not think that it was helpful to his wife's campaign. The Clinton surrogates, however, were very vocal in their criticism of Bernie Sanders calling Hillary Clinton unqualified to be president.

(BEGIN VIDEOTAPE)

MALVEAUX (voice-over): Hillary Clinton today not letting go of charges from Bernie Sanders that she is not qualified to be president.

CLINTON: Seriously, I've been called a lot of things over the years, but unqualified has not been one of them. He doesn't really believe that. This is all pretty silly.

MALVEAUX: The rebuke from the Democratic frontrunner comes as Sanders backs off his earlier criticism of Clinton's qualifications.

SEN. BERNIE SANDERS (D), PRESIDENTIAL CANDIDATE: Does she have the experience? Obviously, she does. She was secretary of state. A U.S. senator. I thought an outstanding first lady in many respects, breaking the mold.

MALVEAUX: Sanders now back to insisting the Democratic race should remain focused on issues, not personal attacks.

SANDERS: Certainly they do not want to have us act like Republicans or embarrassment to this entire country.

MALVEAUX: But there remains a tough battle under way in New York. Both sides are playing up their Empire State connections.

CLINTON: Hello, Buffalo. Oh, my gosh. I cannot tell you how incredibly happy I am to be back here in Buffalo with all of you.

MALVEAUX: While the Brooklyn-born Sanders paid a visit to his childhood home.

SANDERS: I spent the first 18 years of my life in Apartment 2C right here.

BILL CLINTON, FORMER U.S. PRESIDENT: You are defending the people who killed the lives you say matter. Tell the truth.

MALVEAUX: Today the former president trying to move beyond his comments during a campaign stop in Erie, Pennsylvania.

B. CLINTON: I did something yesterday in Philadelphia. I almost want to apologize for it but I want to use it as an example of the danger threatening our country. We all have different experiences. We cannot learn anything unless we listen.

MALVEAUX: Back in New York where Sanders hopes to maintain his momentum after a string of recent victories. His campaign says it is making plans for an open convention.

JEFF WEAVER, CAMPAIGN MANAGER, BERNIE SANDERS FOR PRESIDENT: We're beginning to work on that. In fact, in all likelihood there will be an open convention.

MALVEAUX: Sanders announced Friday that he will visit Vatican City on April 15th just four days before the crucial New York primary. He said while there are areas where he and Pope Francis disagree, he's a big fan.

SANDERS: People think Bernie Sanders is radical. Read what the Pope is writing.

(END VIDEOTAPE)

MALVEAUX: And Hillary Clinton will be here momentarily. She's going to be speaking here in Rochester, New York. She's making two stops here. Earlier she was in Buffalo.

All of this to show, Wolf, that the fight for New York much bigger than New York City -- Wolf.

This important note to our viewers. Both Hillary Clinton and Senator Bernie Sanders, they will be on CNN's "STATE OF THE UNION" this Sunday with Jake Tapper. Please be sure to watch Saturday morning, 9:00 a.m. Eastern.

And Thursday night, don't forget, join us, 9:00 p.m. Eastern for the Democratic presidential candidate's debate live from Brooklyn. This debate comes only days before the critical New York primary.

Coming up next, fresh searches are under way as we speak after the capture of two major suspects linked to the Paris and Brussels massacres. Could one of the so-called -- one of them be the so-called man in the hat shown on surveillance video before and after the airport bombing?